Stelios Papadopoulos, Ph.D., a co-founder of Exelixis, has been a director since December 1994 and the Chair of the Board since January 1998. Dr. Papadopoulos retired as Vice Chairman of Cowen & Co., LLC in August 2006 after six years as an investment banker with the firm, where he focused on the biotechnology and pharmaceutical sectors. Prior to joining Cowen & Co., he spent 13 years as an investment banker at PaineWebber, Incorporated, where he was most recently Chairman of PaineWebber Development Corp., a PaineWebber subsidiary focusing on biotechnology. He joined PaineWebber in April 1987 from Drexel Burnham Lambert, where he was a Vice President in the Equity Research Department covering the biotechnology industry. Prior to Drexel, he was a biotechnology analyst at Donaldson, Lufkin & Jenrette.